Project Summary & Abstract Pragmatic clinical trials aim to test interventions within typical healthcare settings to produce generalizable results. Successfully implementing pragmatic trials requires overcoming a number of challenges, including acquiring data as efficiently and non-intrusively as possible, so as to encourage maximum study participation at lowest cost. Administrative data are a potential solution for some pragmatic trials. These data derive from routine activities in the healthcare system, including clinical care (e.g., billing systems; use of electronic health records). With administrative data, participants can be passively followed over long time periods, potentially with decreased participant burden, decreased loss to follow-up from inability to contact a participant and decreased cost compared to alternatives (e.g., participant interview or review of medical records). All of these features could enhance both internal and external validity and reduce the overall cost of a trial. Limited empirical work exists on the comparative value of various data sources for ascertaining outcomes in pragmatic trials. We are in a unique position to the leverage the Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) trial, a ten-site pragmatic, cluster-randomized trial focused on serious fall injury in community- dwelling older adults, to determine whether outcome ascertainment in pragmatic clinical trials could be simplified through automated data collection, without introducing significant imprecision or bias, thus reducing costs. STRIDE has multiple sources of data including multiple reference standards (adjudicated outcomes; self-reported outcomes) and two administrative data sources (fee-for-service Medicare data; administrative data from clinical trial sites). We will be able to couple currently available administrative data with newly available Medicare Advantage data to have a complete administrative picture of this almost universally Medicare eligible population. Complete data will give us the opportunity to achieve the overall goal of this research proposal, which is to develop a framework for determining whether administrative data can be used in pragmatic clinical trials in a Medicare eligible population to efficiently and accurately ascertain the primary outcome. To achieve this goal, our project has three aims: (1) develop and validate algorithms for detecting serious fall injuries from administrative data against the reference standards of STRIDE events; (2) determine the impact of the algorithms on trial findings; and (3) assess the cost efficiency (savings) of conducting the trial using administrative data.